This invention relates to a method for cleaning apparatus(es) of a chemical plant or hydrocarbon processing plant, wherein cleaning is performed by establishing a closed flow circulation loop.
In the chemical and the hydrocarbon processing industry (e.g. oil field, refining, petrochemical), cleaning of apparatus(es) occurs for different purposes such as maintenance and inspection, or for recovering the performance of said apparatus(es). Such apparatuses include, but are not limited to, heat exchangers, distillation columns, reactors, filters, pumps, heaters, pipelines, vessels, desalters, extractors, separators and the like. The cleaning operation is performed to remove contaminants, foulants, sludge, deposits and the like, which are detrimental both to the operation of the unit and to health and safety of the maintenance personnel.
Generally speaking, fouling of process apparatuses arises from deposition of heavy compounds. These heavy compounds have boiling point or a melting point>100° C. and generally result from degradation of fluids which are part of the process. Sometimes degradation can even lead to coke and coke-like deposits.
All the examples hereinafter reported are to be intended for the mere purpose of illustration and should not be construed as limiting the invention.
Hydrocarbon processing plants suffer from fouling of apparatus(es). Crude oil just as extracted even gives rise to such a problem. For example, oil-gas separators, distillation columns, heat exchangers, filters are subject to this phenomenon. All crude oil processing cycle, from refining to petrochemical plants, as well as energy industry, suffer this problem. When a processing apparatus is fouled, it has to be isolated from the process, emptied from fluids, degassed, disassembled and cleaned; then mounted again in the plant and inserted in the process. Therefore, fouling implies: a) energy efficiency reduction; b) production loss; c) maintenance work; d) waste disposal; e) airborne pollution generation; f) safety concerns; g) reduced environmental performance.
Cleaning of processing apparatus can also be performed during plant turnaround; in this case time for cleaning can be the limiting factor of turnaround duration, which will affect the economics of yearly production. In todays' state of the art, cleaning of apparatuses is performed after degassing in a specific way for each type of apparatus. Generally, washing with water high pressure jet (hydroblasting) is the common choice for cleaning. Finally, all the cleaning methods are time consuming, can be applied to a single apparatus at a time and can lead to apparatus damage (e.g. heat exchanger bundle is damaged upon extraction). Moreover they give rise to environmental and safety concerns, as waste and emissions are generated during the cleaning process and working personnel is exposed to chemical and mechanical risks.
As an exemplary illustration, todays technologies for cleaning heat exchangers in the hydrocarbon processing industry comprise the following operations: a) flushing; b) isolating the equipment from the process and blinding; c) removing the hydrocarbons; d) steaming out for gas and light hydrocarbons removal (degassing); e) unbolting; f) removing covers and distributor; g) extracting the bundle; h) transporting the bundle from plant to washing area; i) hydroblasting; j) transporting the bundle from washing area to plant; k) inserting the bundle; I) inserting new gaskets; m) installing covers and distributor; n) bolting; o) removing blinding; p) air removal and purging; q) inserting the apparatus in the process.
There have been some attempts in the art to develop a cleaning method which would improve the mechanical methods, but these have been unsatisfactory for industrial practices and needs.
Accordingly, there is a continued need in the art for an improved cleaning method, which can avoid all of these pitfalls.